I'm sure there are some costs, but JQ had been scapegoating production/printing costs (he specifically mentioned paper quality a few times) for Marvel's price hike.
My attitude is "ok, I buy that. If you're not giving me paper, I shouldn't be paying for it."
Either he was feeding us all a line of BS from the start or similar costs are mirrored in some way in the production and distribution of a digital book.* None of that changes the fact that customers, myself included, feel that a digital product should be cheaper.
That's why I loved to know what the costs are that are associated with preparing the book for a digital market. Unfortunately, no one is telling. Just like how no one is reporting actual unit sales on digital books.
*At least, I imagine that to be the company line.